This snake-bodied fiend has a six-armed woman's torso, pointed ears, and glittering, otherworldly eyes.
5e SRD
Terrible to behold, a marilith has the lower body of a great serpent and the upper torso of a humanoid female with six arms. Wielding a wicked blade in each of its six hands, a marilith is a devastating foe that few can match in battle.
These demons possess keen minds and a finely honed sense of tactics, and they are able to lead and unite other demons in common cause. Mariliths are often encountered as captains at the head of a demonic horde, where they embrace any opportunity to rush headlong into battle.
The temple was strewn with body parts. We concluded that the cultists had summoned a powerful demon and not lived to regret it. Not wanting to get hacked to pieces ourselves, we cut short our expedition and returned to the village of Hommlet with our tails between our legs. Rufus and Burne had a good laugh at our expense, let me tell you.
Marilith
Demon of Cruelty and Viciousness
Mariliths are six-armed, serpent-like demons that wield lethal, Abyss-forged blades. With these cursed weapons and experience from countless battles, they lead other demons to slaughter virtuous souls. They often command droves of weaker demons.
5e Tools
Powerful infernals with the upper body of a beautiful woman and the lower body of a giant snake
Marilith are powerful infernals with the upper body of a beautiful woman, and the lower body of a giant snake. Their six arms are long and slender, and their skin is a deep red and their scaly snake body has amazing patterns running across its scales. Mariliths are highly intelligent, often using their beauty and charm to manipulate others.
In battle, a marilith attacks with all six of its claws, each inflicting 1d6 points of damage, or weapons held in any or all of its clawed hands. They are skilled with scimitars, spears, and whips, but can wield any weapon with ease. As with most infernals, a marlith can only be damaged by magical weapons.
When encountered, mariliths will attempt to seduce or deceive their opponents before engaging them in battle.
Basic Fantasy Field Guide Omnibus
Six-armed female demon with serpentine lower body, infamous for cruel and ill-tempered nature
Infamous even among demonkind for their cruel and ill-tempered nature, the marilith are invariably female. From the waist up they appear to be a full-figured human female with six arms and skin tones ranging from deep violet to a putrescent green. Below the waist however, they have the coiling body of a large serpent. In melee they prefer to wield a variety of barbed and hooked swords and battle axes or simply constrict their prey with their powerful serpentine tail.
OSRIC